The present invention relates to a capsule composed of a plastic material, and used in particular for infusion and injection bottles and the like.
More particularly, it relates to such a capsule which is formed to maintain a condition of sterilization at an area to be pierced by a needle.
Capsules of the above mentioned general type are known in the art. A known capsule includes the capsule body to be fitted on a neck of a bottle for retaining a pierceable plug in place, and a capsule cap which is fitted on the capsule body.
It is known that bottles for containing drugs such as infusion liquids or the like are generally closed by a pierceable rubber plug which is retained in place by a capsule of aluminum, and the aluminum capsule is secured by seaming to the bottle neck to cover the entire rubber cap. The capsule has a weakening line formed on its central wall for permitting a central portion of the capsule wall to be easily removed so as to give access to the underlying rubber ring and to pierce the latter for drawing off a product.
Aluminum capsules involve, however, some disadvantages. First of all, they cannot be mounted while being maintained in a sterilized environment. The reason is that because the sheet folding operation that is necessary to fix by seaming the capsule to a bottle neck causes a certain quantity of aluminum powder to be produced, whose dispersion in the environment would destroy the sterilized condition. The same as above occurs with lubricant that has to be used in machines for manufacturing aluminum capsules. As a result, aluminum capsules are mounted in a not sterilized environment. Also, it frequently occurs that a user cuts or hurts himself in pulling up this material. It is therefore desirable that a different material, for example a material which does not involve the above described problems could be resorted to, for example, a plastic material.
Several efforts have been made to this extent, but none of them was brought to a successful result. A plastic material in effect either does not withstand such high temperatures as required for autoclaving, or it is expanded and/or distorted to such an extent that it cannot secure sterilized conditions to be maintained inside the capsule. Conversely, when using a material that withstands high temperatures and is of sufficient thickness to avoid excessive distortion, the capsule is too thick and is difficult to rupture for removing the cap. The existing capsule can be improved in some aspects.